Rhinitis is present in 70% of CFS subjects. The investigators have intensively studied the nasal mucosa in CFS rhinitis to evaluate three hypotheses of CFS pathology: (1) immune dysfunction with atopy; (2) mucosal inflammation including viral infections; They propose to prospectively analyze atopy, mucosal inflammation, and neural dysfunction in age- and sex-matched CFS and control groups by using integrated nasal analysis models. They feel strongly that their hypothesis-driven approach will precisely define specific neural pathophysiological mechanisms in CFS, allow pharmacological manipulation of these dysfunctional systems, and potentially lead to the development of simple new diagnostic tests (i.e. nasal provocation) as the means to evaluate future treatments of CFS.